Electrochemical Oxidation of N,N'-Disubstituted Trifluoroethanimidamides. An Approach to N-Substituted 2-(Trifluoromethyl)benzimidazoles
摘要:
Electrochemical oxidation of N,N'-disubstituted trifluoroethanimidamides 11 in dry acetonitrile and in aqueous acetonitrile provided N-substituted 2-(trifluoromethyl)benzimidazoles 15 and N-1-(4-oxo-2,5-cyclohexadien-1-ylidene)-N-2-substituted-2,2,2-trifluoroethanimidamides (p-benzoquinone imine derivatives) 20, respectively. In dry acetonitrile, electron-donating para substituents in the N,N'-diaryl derivatives strongly promoted the formation of benzimidazoles, whereas N-alkyl-N'(4-methoxyphenyl) derivatives provided rather complex mixtures of 11,20, and polymeric compounds. In wet acetonitrile, p-benzoquinone imines 20 were major products regardless of the substituents. An ECEC process via two-electron oxidation is proposed.
Synthesis of N-Substituted 2-Fluoromethylbenzimidazoles via Bis(trifluoroacetoxy)iodobenzene-Mediated Intramolecular Cyclization of N,N′-Disubstituted Fluoroethanimidamides
作者:Yongming Wu、Jiangtao Zhu、Haibo Xie、Zixian Chen、Shan Li
DOI:10.1055/s-0029-1218377
日期:2009.12
A mild and efficient method for the synthesis of N-substituted 2-fluoromethylbenzimidazoles via [bis(trifluoroacetoxy)-iodo]benzene-mediated intramolecular cyclization of N,N'-disubstituted bromodifluoro (or trifluoro) ethanimidamides was described.
Defluorinative Alkylation of Trifluoromethylbenzimidazoles Enabled by Spin-Center Shift: A Synergistic Photocatalysis/Thiol Catalysis Process with CO<sub>2</sub><sup>•–</sup>
direct single C(sp3)–F bond alkylation of trifluoromethylbenzimidazoles under a photoinduced thiol catalysis process. The CO2 radical anion (CO2•–) proved to be the most efficient single-electron reductant to realize such a transformation. The spin-center shift of the generated radical anion intermediate is the key step in realizing C–F bond activation under mild conditions with high efficiency.
Defluoroalkylation of Trifluoromethylarenes with Hydrazones: Rapid Access to Benzylic Difluoroarylethylamines
作者:Cecilia M. Hendy、Cameron J. Pratt、Nathan T. Jui、Simon B. Blakey
DOI:10.1021/acs.orglett.3c00126
日期:2023.3.10
Here, we report an efficient and modular approach toward the formation of difluorinated arylethylamines from simple aldehyde-derived N,N-dialkylhydrazones and trifluoromethylarenes (CF3-arenes). This method relies on selective C–Fbondcleavage via reduction of the CF3-arene. We show that a diverse set of CF3-arenes and CF3-heteroarenes react smoothly with a range of aryl and alkyl hydrazones. The β-difluorobenzylic
Synthesis of 2-trifluoromethyl benzimidazoles, benzoxazoles, and benzothiazoles <i>via</i> condensation of diamines or amino(thio)phenols with CF<sub>3</sub>CN
method is developed for the synthesis of 2-trifluoromethyl benzimidazoles, benzoxazoles, and benzothiazoles in good to excellent yields by the condensation of diamines or amino(thio)phenols with in situ generated CF3CN. Additionally, the synthetic utility of the 2-trifluoromethyl benzimidazole and benzoxazole products is demonstrated via gram scale synthesis. The mechanisticstudy suggests that the reaction